Dr Thomas has seen dramatic changes around him since leaving the Adelaide suburb of Fullerton after finishing his University of Adelaide doctorate in mechanical engineering in 1978.

In his early student years slide rules were the only tool available for calculation. "By the time I finished post-graduate, we had calculators," Dr Thomas said.

"The other was computers. We had huge computers which we would submit programs in with punch cards; you would have a shoebox full of cards. Then you would wait a few hours to get a response out. Now, of course, you have more computing power on your desktop than we could ever have imagined back then.

"I can also remember when I was very, very young, the neighbours having ice delivered to their house because they didn't have a refrigerator; they had an ice box. And I can remember the milkman would come in the middle of the night to leave milk, and he used a horse-drawn cart to deliver to the neighbourhood.

"I have seen a lot of change in technology over my lifespan."

Dr Thomas was back in Australia over the Christmas holidays to visit his elderly mother who still lives in Adelaide. While helping her with her care Dr Thomas became acutely aware of the challenges facing older people, not only in Australia.

"Commercial enterprises are becoming totally reliant on computer systems and internet access," Dr Thomas said. "For example, if you want to run a bank account today, you have to have a cell phone.

"I get very frustrated by this. I think it's very presumptuous for banks, for example, to assume that everyone has a cell phone. Some seniors aren't comfortable with a cell phone and don't want one, and are entitled to that, yet you have these organisations that immediately assume you have to have a cell phone for any kind of transaction."

He has been confronted by the challenges of food packaging while shopping for his mother. "They are packaged in ways that are almost impossible to get into and that provides huge challenges for elderly people," Dr Thomas said.

As to the shopping experience, with the reliance on "bricks and mortar" stores decreasing as online shopping becomes the norm, "I think that is going to be a challenge for senior people because they're not necessarily comfortable buying through the internet," Dr Thomas said. "They are accustomed to walking the aisles of the grocery story, for example, and trying things on and picking what they want. That's going to be relegated to the past and I think it's going to be a big challenge for a lot of people."

He also laments the lack evidence based thinking and the amount of fake news among the broader community. "We don't teach rational thought that comes with scientific education," Dr Thomas said.

Dr Thomas wants Australia's grandparents to turn this around. "I urge everyone to encourage their children and grandchildren to study science. You cannot survive (in the modern, technology world) without having some understanding of science and mathematics.

"We have a culture where we don't ascribe enough value to evidence based thinking. You have these extraordinary fake news stories getting perpetuated through the internet which gains traction, even though they are utterly nonsense. Some politicians in the US are very schooled at exploiting this; we have a president that exploits it.

"I think it's really important that we teach people to value evidence based thinking, empirical evidence and respect for facts, true facts, not fake news," he added.

He also enthuses Australia's younger generations to aim high. "The sky isn't the limit, based on my own experience," he said. "I encourage young people to follow their dreams and bring them to reality because I think it's important they have hope for the future."

Dr Thomas remains resident in America as his wife, Shannon Walker, 53, is also a NASA astronaut. She flew eight years ago and wants to fly again next year. "If you are in the space fight business, you have to be in Houston, Texas if you want to be an NASA astronaut," Dr Thomas. "So, for the immediate future I will staying Houston to support her.

"I retired from the agency about three years ago," he added. "I had four great flights, four more than I ever thought I would get, so I have no complaints."

Dr Thomas still retains a keen interest in Australia's progression in space programs. He said he was one of many voices that in recent years has pushed the Federal Government to form a national space agency to collect satellite data, for communication, and for environmental, strategic and national security monitoring.

"Space is the modern, critical infrastructure that countries need in order to function in the modern world," Dr Thomas said. "I have pushed very hard for Australia to embrace that and have an in-country capability and infrastructure built around the space sector."